Rumjanzew started in Kolomna in December 2007 for the first time in the World Cup and took 23rd place over 10,000 m in the B group. At the all-around world championship in Hamar in 2009 , he achieved 22nd place. The following year he ran there in the all- around European championship on the 20th place. In his first Olympic participation in 2010 in Vancouver , he came in 13th place over 10,000 m. In the 2010/11 season he won in Moscow in the team pursuit together with Ivan Skobrew and Pavel Baynov his first World Cup victory. At the individual distance world championships in 2011 in Inzell he finished 15th over 10,000 m and sixth place in the team pursuit and at the individual distance world championships in 2013 in Sochi he finished 13th over 5000 m and ninth place over 10,000 m. In the 2013/14 season he achieved eighth place in the overall World Cup over 5000/10000 m with two top ten placements. He achieved his first podium finish in the individual World Cup with third place over 5000 m in Heerenveen . At the season highlight, the 2014 Winter Olympics in Sochi, he finished 11th in the 5000 m and sixth in the team pursuit. In the following season he was third in the team pursuit in Obihiro and second in the 5000 m and third in the 10,000 m in Seoul and thus reached fifth place in the overall World Cup over 5000/10000 m at the end of the season. At the individual distance world championships in 2015 in Heerenveen, he finished tenth over 5000 m and fifth over 10,000 m. The following year he was third in the team pursuit at the World Cup in Heerenveen and sixth in the team pursuit at the individual distance world championships in Kolomna. In the 2017/18 season he achieved three top ten results, including second place over 5000 m in Minsk , fifth place in the overall World Cup over 5000/10000 m. In January 2018 he won the 5000 m European championships in Kolomna and the silver medal in the team pursuit.
At the beginning of the 2018/19 season Rumyantsev won his second World Cup victory in the team pursuit in Obihiro , where he also took second place in the 5000 m. In the further course of the season he ran in Tomaszów Mazowiecki to third place in the team pursuit and second place over 10,000 m and in Hamar to second place over 5000 m. At the end of the season he won the overall 5000/10000 m World Cup. At the individual distance world championships in February 2019 in Inzell , he won the bronze medal in the team pursuit. He also took fifth place over 10,000 m and fourth place over 5000 m.
At Russian championships Rumyantsev won five times over 10,000 m (2011, 2014, 2015, 2018, 2019) and twice over 5000 m (2018, 2019).
Personal bests
00500 m 00:37.60 sec. (installed on February 7, 2009 in Hamar)
01000 m 01: 14.71 min. (installed on December 19, 2010 in Klobenstein)
01500 m 01: 46.22 min. (installed on February 7, 2020 in Calgary)
03000 m 03: 39.28 min. (installed on November 25, 2017 in Calgary)
05000 m 06: 10.78 min. (installed on March 9, 2019 in Salt Lake City)
10000 m 12: 57.45 min. (installed on November 19, 2017 in Stavanger)
Participation in World Championships and Olympic Winter Games
Russia
Obihiro